1. Field of the Invention
The present invention relates to vehicle stop detecting apparatus for detecting a stop condition of a vehicle.
2. Description of the Related Art
In the case of mounting a video equipment such as a television receiver on a vehicle, it is necessary from a safety point of view to take safety measures so that a driver cannot see a picture, especially, a moving picture to be displayed on the video equipment during running of the vehicle. As an example of such safety measures, there has been proposed a vehicle stop detecting apparatus for detecting a position of a parking brake lever and generating a vehicle stop signal when the parking brake lever is in a position corresponding to a parking brake operative condition. In the conventional vehicle stop detecting apparatus, when the vehicle stop signal is not generated, it is determined that the vehicle is running, and the supply of a video signal to a display such as CRT and LCD of the video equipment is cut off, or a power supply of the video equipment is cut off.
FIG. 1 shows an example of such a vehicle stop detecting apparatus. Referring to FIG. 1, an unlocking depression type brake operation detecting switch 3 is provided on a cabin floor surface 2 under a parking brake level 1. As shown in FIG. 2, one end of the brake operation detecting switch 3 is supplied with a power supply voltage +B through a parking brake lamp 4, and the other end is grounded. The power supply voltage +B is an output voltage of an on-vehicle battery, and it is supplied through an accessory switch (not shown) to the switch 3. A detection output is obtained from the one end of the brake operation detecting switch 3, that is, a connection line to the parking brake lamp 4.
When the parking brake lever 1 is in a position corresponding to a parking brake inoperative condition, the brake operation detecting switch 3 is depressed by the parking brake lever 1 to be turned off. Accordingly, the parking brake lamp 4 is turned off, and a detection output level is a power supply voltage level. On the other hand, when the parking brake lever 1 is operated against a biasing force of a biasing member 5 as shown in FIG. 1, and is located in a position corresponding to a parking brake operative condition, the brake operation detecting switch 3 is tuned on. Accordingly, the parking brake lamp 4 is turned on, and the detection output level becomes an earth level. According to the earth level as the vehicle stop signal, inhibition of displaying of the picture is controlled.
However, in the above conventional vehicle stop detecting apparatus, if the detection output line is not connected to the one end of the brake operation detecting switch 3 but directly connected to the earth, the detection output level is maintained at the earth level even when the parking brake lever 1 is in the position corresponding to the parking brake inoperative condition, thereby making a generating condition of the vehicle stop signal. Thus, a user can easily obtain a picture display condition even during running of the vehicle by modifying a wiring connection as mentioned above. In this manner, the above-mentioned safety measures in the prior art are insufficient.